B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Introduction on the Voltage Introduction on the Voltage Control ConferenceControl Conference
Steve Enyeart, Dmitry Kosterev, Terry Oliver,
Eric Heredia, Bart McManus and Steve Hitchens
Bonneville Power Administration
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 2
Voltage Control Voltage Control ––
Session OverviewSession Overview1.
Grid operator’s perspective on voltage control
requirements and operational experiences in the Pacific Northwest
2.
Manufacturer’s perspective on voltage control and equipment capabilities
3.
Wind power plant operator’s perspective on voltage control
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 3
Presentation SubjectPresentation Subject
The presentation focus is on control needs for “stability”
time
frame – i.e. making sure that the power system survives and
performs during the power system disturbances
Specifically, the presentation will focus on:
– Voltage stability and controls
– Monitoring and modeling
The presentation will NOT discuss:
– Wind generation balancing and regulation (“capacity”)
– New transmission needed to accommodate wind
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 4
Wind in BPAWind in BPA
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 5
Wind in BPAWind in BPA
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 6
Many of BPA Paths are StabilityMany of BPA Paths are Stability‐‐LimitedLimited
California – Oregon Intertie
Pacific HVDC Intertie
Montana ‐
Northwest
Cross‐Cascades North
Cross‐CascadesSouth
Wind
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 7
Pacific AC and DC IntertiesPacific AC and DC Interties
California – Oregon Intertie (COI) – three AC lines from Pacific
Northwest to Northern California
– rated at 4,800 MW
Pacific HVDC Intertie (PDCI) – a two‐pole DC line from Pacific
Northwest to Los Angeles
– rated at 3,100 MW
Operating limits are usually lower, mainly due to voltage
stability constraints
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 8
August 10 1996 OutageAugust 10 1996 Outage
425
450
475
500
525
550
575
15:41:00.00 15:42:00.00 15:43:00.00 15:44:00.00 15:45:00.00 15:46:00.00 15:47:00.00 15:48:00.00 15:49:00.00 15:50:00.00 15:51:00.00
Volta
ge [k
V]
Time
Slatt Voltage
Keeler-Allston outage
McNary tripping begins
COI sepration
Oscillations
“Those who forget the past are condemned to repeat it”
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 9
August 10 1996 OutageAugust 10 1996 Outage
Lessons learned:
– There are interactions among several transmission paths in Pacific
Northwest, on‐line generation and load levels
– Dynamic reactive reserves in lower Columbia are critical to support the
high power transfers
– Operating in POWER FACTOR instead of VOLTAGE control is highly
detrimental
Outage
– A combination of voltage collapse and unstable oscillations resulted in
COI separation and PDCI shutdown
– 28,000 MW of load lost, 7.5 million customers
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 10
Impact of August 10 1996 OutageImpact of August 10 1996 Outage
Interties were de‐rated:– COI was de‐rated by 33%– PDCI was de‐rated by 33%
Significant investments were made by BPA to improve voltage
stability in the Pacific Northwest– Synchronous condenser capabilities at two Lower Columbia plants
– Shunt capacitor additions– AC Reactive RAS and Fast AC Reactive Insertion– PDCI control modification
Operating procedures– COI / PDCI Operating Nomogram
– Dynamic reserve monitoring for generators in Lower Columbia
– Equivalent unit monitoring for voltage swing support
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 11
Pacific AC and DC IntertiesPacific AC and DC Interties
Typical COI + PDCI Operating Nomogram
2011 BPA invested into Bakeoven series capacitors in both
John Day –
Grizzly lines to improve power delivery to COI
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 12
Reliability StandardsReliability Standards
We plan and operate the power system to meet the Reliability
Standards, which set system performance criteria for normal
and outage conditions
Reliability sanctions – we live in the world of mandatory
reliability standards as a result of the 2003 Northeast blackout
– February 26, 2008 Florida outage:
– 3,560 MW of load and 4,300 MW of generation
– FPL settled with FERC for $25M, ($10M – US Treasury, $10M – NERC,
$5M –
reliability improvements)
– Florida Public Service Commission asked FPL to refund $13.9 M to
affected customers
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 13
Voltage ControlVoltage Control
Voltage control goes beyond maintaining plant
voltages during power ramps
– This is given
Voltage control is helping the system to survive “macro”
disturbances
– the system ability to survive disturbance sets that
System Operating Limits
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 14
““MacroMacro””
Stability Issues Stability Issues
420
440
460
480
500
520
540
560
670 675 680 685 690 695 700 705 710 715 720
Time (sec)
Malin Voltage ‐ June 14, 2004 event
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 15
““MacroMacro””
Stability Issues Stability Issues
526
528
530
532
534
536
538
540
542
544
546
0 10 20 30 40 50 60
Malin Voltage
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 16
““MacroMacro””
Stability Issues Stability Issues
360
400
440
480
520
560
13:47:25 13:47:30 13:47:35 13:47:40 13:47:45 13:47:50 13:47:55 13:48:00 13:48:05 13:48:10 13:48:15
Volta
ge [k
V]
Time(hh:mm:ss)
FIDVR Event in Southern California
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 17
2006 Study2006 Study……
How integrating 3,000 MW of wind generation will
impact the system “macro”
stability
Conclusion 1:
The Interties will be de‐rated if the wind power plants do not provide dynamic voltage control
– Voltage stability– Damping of inter‐area oscillations
– Transient stability
And we saw this happened at local scale
...
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 18
Type 2 plantType 2 plant
50 100 150 200 250234
236
238
240
242Voltage
Time (min)
Vol
tage
(kV
)
50 100 150 200 2500
50
100Active Power
Time (min)
Pow
er (M
W)
50 100 150 200 250-30
-20
-10
0
10Reactive Power
Time (min)
Rea
ctiv
e (M
VA
R)
As POI voltage declines
…WPP draws larger
amount of reactive
power
Early plants do not have
STATCOMs and use only
shunt caps
Operate mainly in power
factor mode
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 19
Wind Ramp EventWind Ramp EventThis is actual data, not
simulations
Different plant
All lines in service
Wind ramping up event
Wind power plants are in
power factor
control mode
The issues have been
addressed
0 50 100 150 200 250 300234
236
238
240
242
244
Time (min)
Vol
tage
(kV
)
Voltages
0 50 100 150 200 250 3000
100
200
300
400
500Wiind Total Power
Time (min)
Pow
er (M
W)
0 50 100 150 200 250 300-20
-10
0
10
20Wiind Total Reactive Power
Time (min)
Rea
ctiv
e (M
VA
R)
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 20
Wind Ramp EventWind Ramp EventPV‐Curve for same event
0 50 100 150 200 250 300 350 400 450233
234
235
236
237
238
239
240
241
242
243PV Plot - Voltage versus Wind Total
Power (MW)
Vol
tage
(kV
)
The edge
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 21
……2006 Study2006 Study
Conclusion 2:
To integrate reliably 3,000 MW of wind
– Wind power plants have adequate reactive capabilities
– Wind power plants are operated in voltage control
mode
New wind generation technologies are capable of voltage control, and can offer performance better than synchronous machines.
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 22
Voltage Control RequirementsVoltage Control Requirements
BPA requires wind power plants to provide voltage
control and reactive power to support the grid – just like other large generation projects
How much reactive is needed: – Dynamic reactive sized to provide continuous +/‐
0.95 power
factor at 34.5‐kV bus
– Switched shunts to compensate for reactive power losses
between WTGs and Point Of Interconnection, high switching
duty
How to control reactive resources:– Operate in continuous (no dead‐band !) voltage control mode,
control POI voltage to BPA schedule with reactive droop
– Shunt switching to maximize the availability of dynamic
capabilities at the plant
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 23
Two 9 MVAR switched shunts capacitors to compensate for steady-state reactive
losses, high switching duty(can be on BPA HV bus for several plants)
W
Wind PowerPlant Voltage
Controller
V
QQLDC
BPA Voltage Schedule(Raise / Lower)
W
+/- 0.95 pf (+/- 33 MVAR)continuouslycontrollable
100 MW Type 3 or 4 Wind Generator Example100 MW Type 3 or 4 Wind Generator Example
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 24
Three 10 MVAR switched shunts capacitors to compensate for steady-state
reactive losses, high switching duty(can be on BPA high side)
Wind PowerPlant Voltage
Controller
V
QQLDC
BPA Voltage Schedule(Raise / Lower)
100 MW Type 2 with STATCOM100 MW Type 2 with STATCOM
W
W
1.0 pf
+/- 16 MVARSTATCOM
+/-32 MVAR 2-second overload capability
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 25
Voltage ControlVoltage Control
Power Plant POI Reactive Power
POI Voltage
Power Factor /VAR Control
Low Side Voltage Control
Line Drop Compensation
High Side Voltage Control
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 26
Voltage ControlVoltage Control
Power Plant POI Reactive Power(100 MW plant)
POI Voltage
238-kV
246-kV
242-kV243-kV
235-kV
239-kV
+30 MVAR–30 MVAR
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 27
Observed ChallengesObserved Challenges
A plant is commissioned in high side voltage control
Plant experiences large MVAR swings for small voltage fluctuations
Power plant operator turns plant into MVAR control
BPA contacts plant operator, eventually the plant is set to a “hybrid”
mode – MVAR controller with
voltage over‐ride
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
VQ Characteristic of a WPP with Type 3 WTGs
230
232
234
236
238
240
242
244
246
248
250
-40 -20 0 20 40
Reactive Power (MVAR) for Active Power > 40 MW
Volta
ge (k
V)
Plant Reactive Power
-40
-30
-20
-10
0
10
20
30
40
7/12/20110:00
7/12/20114:48
7/12/20119:36
7/12/201114:24
7/12/201119:12
7/13/20110:00
7/13/20114:48
7/13/20119:36
7/13/201114:24
7/13/201119:12
7/14/20110:00
230-kV Bus Voltage
238
239
240
241
242
243
244
245
246
7/12/20110:00
7/12/20114:48
7/12/20119:36
7/12/201114:24
7/12/201119:12
7/13/20110:00
7/13/20114:48
7/13/20119:36
7/13/201114:24
7/13/201119:12
7/14/20110:00
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
VQ Characteristic of a WPP with Type 3 WTGs
230
232
234
236
238
240
242
244
246
248
250
-40 -20 0 20 40
Reactive Power (MVAR) for Active Power > 40 MW
Volta
ge (k
V)
230-kV Bus Voltage
238
239
240
241
242
243
244
245
246
8/13/201112:00
8/13/201116:48
8/13/201121:36
8/14/20112:24
8/14/20117:12
8/14/201112:00
8/14/201116:48
8/14/201121:36
8/15/20112:24
8/15/20117:12
8/15/201112:00Plant Reactive Power
-40
-30
-20
-10
0
10
20
30
40
8/13/20110:00
8/13/20114:48
8/13/20119:36
8/13/201114:24
8/13/201119:12
8/14/20110:00
8/14/20114:48
8/14/20119:36
8/14/201114:24
8/14/201119:12
8/15/20110:00
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 30
Observed ChallengesObserved Challenges
Reactive power deliverability
Voltage control dead‐bands
Coordination of dynamic reactive and shunt capacitor switching within a plant
Shunt capacitor availability
How to test the voltage control response ?
B O N N E V I L L E P O W E R A D M I N I S T R A T I O N
Slide 31
2011 Study2011 Study
How integrating 8,000 MW of wind generation
will impact the system “macro”
stability
Studies done up to now has not shown “macro” stability issues with 8,000 MW of wind in Pacific Northwest (as long as wind power plants are in
agreements with BPA voltage control requirements and study models are correct)
…
Will reality agree with the studies ?
